1. Technical Field of the Invention
The invention relates to a cosmetic or dermatological composition containing a carrier comprising at least one fatty phase characterized in that it contains at least one derivative or a mixture of derivatives of 1,7-diphenyl-3,5-heptanedione having a particular structure and at least one oil having, in its structure, at least one amide unit, and its cosmetic and dermatological uses, in particular against the harmful effects of UV radiation and pollution on human keratinous materials, and more particularly for the prevention and/or treatment of photoaging of the skin.
The invention also relates to a method for solubilizing a derivative or a mixture of derivatives of 1,7-diphenyl-3,5-heptanedione having a particular structure with at least one oil having, in its structure, at least one amide unit.
2. Description of the Prior Art
In the course of time, various signs appear on the skin which are very characteristic of aging, resulting in particular in a modification of the structure and the functions of the skin.
This aging, which is of a physiological nature, may be accelerated by environmental factors such as repeated exposure of the skin to sunlight, and in particular to ultraviolet A radiation, to pollution in particular, or to diesel particles or to cigarette smoke. The environmental action on the constituents of the skin (fibers, cells, enzymes) and on the sebum secreted by the skin causes, in particular, the formation of oxygenated free radicals. Now, these radicals cause substantial oxidative damage, in particular in the cell membranes (permeability of the membranes), the cell nuclei (destruction of DNA), and the tissues, in particular the connective tissue (degradation of the elastin and collagen fibers). This damage leads in particular to a loss of firmness and elasticity of the skin.
It has, in addition, been suggested that the free radicals could be involved in the process of production of melanin leading to the pigmentation of the skin.
The mechanism of formation of melanin is particularly complex and schematically involves the following main steps:tyrosine→Dopa→dopaquinone→dopachrome→melanin
Tyrosinase (monophenol dihydroxyphenylalanine: oxygen oxidoreductase EC 1.14.18.1) is the key enzyme involved in this succession of reactions. It catalyses in particular the reaction of conversion of tyrosine to Dopa (dihydroxyphenylalanine) by virtue of its hydroxylase activity. Now, some authors think that the step of hydroxylation of tyrosine to Dopa could be initiated by OH° radicals (C. Montastier et al., Méthodes d'objectivation des effets des agents dépigmentants chorl'homme [Methods of objectifying the effects of depigmenting agents in humans], J. Med. Esth. and Chir. Derm., Vol. XXII, 86, June 1995, pp. 93-103).
The free radicals formed under the effect of environmental factors could therefore cause an increase in the formation of melanin, and thus cause or intensify certain undesirable hyperpigmentation such as idiopathic melasma, which occur during pregnancy (“mask of pregnancy” or chloasma) or during oestro-progestational contraception, or localized hyperpigmentation such as the senile pigmented spots termed actinic lentigines.
It is therefore necessary to protect the skin against these free radicals.
This protective function is usually provided by enzymes present in the cutaneous tissue. However, under certain circumstances, the role of these enzymes is not sufficient to completely block the destructive action of free radicals.
The tetrahydrocurcuminoids obtained by the reduction of curcumin or which are synthesized as described in the articles “Synthesis and antibacterial activity of tetrahydrocurcuminoids; S Venkateswarlu, M Rambabu, G V Subbaraju and S Satyanarayana; Asian Journal of Chemistry-2000-1-141-144”, “Synthesis of naturally occurring curcuminoids and related compounds; U Pedersen, P B Rasmussen, S O Lawesson; Liebigs Ann. Chem.-1985-1557-1569, patent applications JP 02051595, JP 02069431, JP 02049747 and JP 02128133, patent U.S. Pat. No. 5,266,344 and application WO 00/61162 have already been used in cosmetics as agent for protecting skin against the effects of UV radiation (JP 06128133), as antioxidant and/or as anti-free radical agents in patent application WO 97/03674. They are also used in application WO 99/55352 in lightening or depigmenting compositions for the skin in combination with a depigmenting agent.
There are also known from patent application EP 1108419 cosmetic compositions for topical application to the skin, containing at least one tetrahydrocurcuminoid such as tetrahydrocurcumin and/or tetrahydrodemethoxycurcumin and/or tetrahydrobisdemethoxycurcumin or mixtures thereof. They are used for protecting human keratinous materials against the harmful effects due to various environmental factors: UV radiation, smoke, ozone, polluting substances. They are also recommended for combating the formation of free radicals and intrinsic or extrinsic skin aging. It is also known, in application WO 99/22728, that tetrahydrocurcuminoids are also active as 5α-reductase inhibitors.
During its research studies, the applicant observed that certain derivatives of 1,7-diphenyl-3,5-heptanedione, including tetrahydrocurcuminoids, which are active as antioxidants and/or as anti-free radical agents, substantially lost their efficacy in common cosmetic carriers comprising at least one fatty phase (in particular emulsions) because of their very low solubility in most oils commonly used and led to microscopically unstable formulations over time because they crystallize and form a deposit in the carrier. This instability of the tetrahydrocurcuminoids can, in addition, modify the appearance of the compositions containing them.
Among the oils commonly used in cosmetics, there may be mentioned mineral oils such as those of the paraffin type (MARCOL 82 from Esso) or hydrocarbons such as isohexadecane (PERMTHYL 101A from BAYER); oils of plant origin such as refined apricot stone oil (MP301 from Nestle); liquid waxes such as liquid jojoba wax (Pure Golden Jojoba Oil from DESERT WHALE); fatty acid esters such as dicaprylyl maleate (BERNEL ESTER from DOM), dicaprylyl carbonate (CETIOL CC from Cognis), tridecyl trimellitate (DUB TMTD from Stearine Dubois), dioctyl maleate (CERAPHYL CM5 from Rhodia Chimie), isopropyl palmitate, isononyl isononanoate (WICKENOL 151 from Alzo) and C12-C15 alcohol benzoates (FINSOLV TN from WITCO); C6-C18 fatty acid triglycerides such as caprylic/capric acid triglyceride (MYRITOL 318 from Cognis).